Golang micro-app, which check whether an IP address or a network belongs to a given network.
I use it as an addition to standard ipcalc binary distributed with common Linux distributions.
Simply copy it to your ~/bin directory, and you'll all set (assuming your ~/bin directory is in your PATH)
I use it inside of my Linux desktop deployment automation.
$ ipcalc-contains 192.168.0.0/24 192.168.0.10
CONTAINS! Network 192.168.0.0/24 contains IP 192.168.0.10
$ ipcalc-contains 192.168.0.0/24 192.168.1.10
NOPE! Network 192.168.0.0/24 DOES NOT contain 192.168.1.10
$ ipcalc-contains 192.168.0.0/20 192.168.12.0/30
CONTAINS! Network 192.168.0.0/20 contains 192.168.12.0/30
$ ipcalc-contains 192.168.1.0/20 192.168.12.128/10
NOPE! Network 192.168.1.0/20 DOES NOT contain 192.168.12.128/10